Method of and apparatus for minimizing deposition of carbonaceous material



Jan. 3, 1950 R T. SAVAGE 2,493,035

METHOD OF AND APPARATUS FOR MINIMIZING DEPOSITION OF CABBONAGEOUS MATERIAL Filed Dec. 19, 1947. 2 Sheets-Sheet 1 INVENTOR.

[B92500 [fir age ATTORNEY.

Jan. 3, 1950 R. T. SAVAGE v METHOD UP AND APPARATUS FOR MINIMIZING DEPOSITION OF CARBONACEOUS MATERIAL 2 Sheets-Sheet 2 Filed Dec. 19, 1947 INVENTOR. Reuben e /mg'e ATTORNEY.

Patented Jam. 3, 1950 mz'rnon or AND APPARATUS- FOR MINI- mzmo nsrosrnos or CABBONACEOUS MAT Reuben '1. Savage, Bidley Park, Pa., assignor to Houdry Process Corporation, Wilmington, Del., a corporation of Delaware Application December 19, 1947, Serial No. 792,809

My invention relates to a hydrocarbon conversion systennand has particular reference to a method ofand apparatus for at least substantially preventing deposition of carbonaceous material on the interior surface of a conversion housing or on selected surfaces interiorly thereof. 'As known in the art of converting hydrocarbons, it is desirable, under some circumstances, for atomized liquid hydrocarbon material to form at least a part of the total hydrocarbon charge which is engaged with heated contact material adapted to gravitate or flow through a housing while having conversion temperature. In a process of this character, the atomizer for the liquid hydrocarbon material is suitably located in a chamber of said housing which, in part, is traversed by atomized liquid material ejected by the atomizer into engagement with at least a substantial portion of the gravitating contact material. This atomized liquid material is ejected from the atomizer at high velocity, some of whichjin an unintended or undesired manner and, unless prevented, migrates or tends to migrate to the interior housing surface and/or the surface or surfaces of one or more other members disposed within said housing. In'fne event that such atomized liquid material reaches said surface or surfaces, as the conversion operation proceeds, there is a resultant undesired accumulation of carbonaceous material thereon.

In accordance with my invention. a suitable casing defining one or more ports is located in the aforesaid chamber and, to this casing, vapors such, for example as hydrocarbon vapors are passed in quantity and at pressure sufllcient to produce a stream of high velocity vapors which are elected in a directional manner from the cas-. ing so that they pass into the path followed by atomized liquid material migrating or tending to inigrate to such a surface as aforesaid.

This stream of vapors deflects at least a substantial portion of such atomized liquid material and effectively minimizes the aforesaid undesired formation of carbonaceous material.

More particularly, in accordance with my invention, the stream of vapors ejected from the aforesaid port-defining casing is circumferentially complete and, preferably, this vapor stream is directed downwardly around the atomizing zone so as to prevent or substantially minimize migration of atomized liquid material to the interior surface of the reaction or conversion housing.

Various other objects and advantages of my invention will become apparent from the following detailed description.

9 Claims. (Cl. 196-52) My invention resides in the method of and ap paratus for minimizing deposition of carbonaceous material on one or more surfaces within a conversion housing, features and arrangements of the character herinafter described and claimed.

For an understanding of my invention and for an illustration of one form of apparatus with which the invention may be practiced. reference is to be had to the accompanying drawings, in which:

Fig. 1 is a. vertical sectional view, partly in elevation, showing a conversion housing and an associated arrangement for producing a'stream of high velocity vapors;

Fig. 2. is an enlarged, vertical sectional view. partly in elevation, showing a part of the apparatus illustrated in Fig. 1;

Fig. 3 is an enlarged horizontal sectional view, taken on the line 3-3 of Fig. 1 looking in the direction of the arrows; and

Fig. 4 is an horizontal sectional view, partly in plan, taken on the line 4-4 of Fig. 2 looking in the direction of the arrows.

In my pending application Serial No. 766,714, filed August 6, 1947, I have disclosed a process of andapparatus for converting hydrocarbon material. For purposes of explanation, the present invention is described in connection with a 'process and apparatus of the character described in said pending application.

housing I in suitable manner, as by aninlet pipe" 2 extending through the top housing wall at the center thereof. As shown, a shallow receptaclelike member 3 may be suitably supported in the upper portion of the housing i, said member 3 having a central discharge pipe 4 opening therethrough and extending downwardly therefrom. The lower end of the pipe 4 may be frusto-conical for the reception of a suitably supported conical member 5 which has external diameter suitably less than the internal diameter of said lower end of the pipe 4. Accordingly, the pipe 4 and the conical member 5 define an annular passage which should have uniform width throughout the circular length thereof.

bon material which is at least partly in the liquid bed of contact material horizontally disposed in the housing I and suitably secured to the interior surface thereof. While the contact material falls freely as the described curtain below the plane of the annular passage 8, it is engaged by liquid hydrocarbon material after atomization thereof by the aforesaid atomizer A, which, as shown, is supported interiorly of the tubular curtain B.

In view of the foregoing, it clearly appears thattheatomizeraisdisposedinachamber Dofthehousing l,saidchamberDbeingbounded, at its lower end, by the zone defined by the upper surface of the bed B and, at its upper end, by the aforesaid zone defined by the receptacle 3.

If desired, a plurality of pipes i may be spaced uniformly around the interior surface of the housing I. The upper ends of these pipes 9 communicate with the chamber defined by the member I, which may support said pipes, and the lower ends thereof terminate at the upper surface of the aforesaid bed of contact material, said Pip s being adapted to be traversed by a portion, preferably a minor portion, as 20% more or less of the total amount of contact material gravitating through the housing I. The pipes 9, when utilized, contribute as regards maintenance of the surface of the bed B at a level approximately that of the lower ends of said pipes.

The aforesaid tube sheet 8 supports a plurality of suitably spaced depending pipes to which open therethrough. The contact material passes through these pipes to and thereafter, in known manner, may be discharged from the housing I for passage through a conduit III which should contain a valve llla' utilizable for controlling the flow oi contact material therethroush so that the contact material forming the bed B is restricted or impeded as it moves downwardly in solid bed fashion under the influence of gravity.

matically indicated, the aforesaid sheet 0 I 'form of atomizer herein shown, although not may support a plurality of tubes II which upstand therefrom and open therethrough, the tubs ll supporting a plurality of suitably arranged channel members II, or equivalent, which are disposed in inverted relation so'that, in known manner, they may be utilized for disengagement or vapors from the contact material, the vapors thereafter entering the tubes H by way of pessages llo formed, respectively, therein. A pipe It opens through the wall of the housing I below the tube sheet I and communicates with the space above the adjacent conical piles of contact material. This pipe I! may have associated therewith a control valve i4 and is adapted to receive and conduct the converted vapors to any suitable destination.

The atomizer A hereinbefore referred to should be one which produces fog, mist, spray or other liquid particles having suitable dimensions from the liquid hydrocarbon material admitted thereto.

As shown in Fig. 2, the atomizer A comprises a casing Ii having a top wall I through which the lower end of the aforesaid pipe 1 opens and to which said pipe is secured. The casing II has a lower wall ll above which said casing ll comprises circular portions lie and lib related to each other in right-angle relation. In the necessarily, a row of ports or passages llc open through the respective casing portions Ila and lib, these ports [5c being alined in sets. Hydrocarbon material admitted by the pipe I to the casing it passes to and through each of said ports lie. The atomizer A is located interiorly of the tubular curtain S a suitable distance below the annular passage 6 and, preferably, said atomizer A is so positioned .that its rows of ports lie, or

Adjacent the lower end of the housing I, any

suitable arrangement may be provided for disengaging cracked or converted vapors from the contact material C. To this end, as diagramstated. Extending from the exterior of the hous-' equivalent, are concentrically related-to the curtain S.

In accordance with my invention and for the reasons hereinafter stated, a stream of hydrocarbon vapors is directed downwardly around the aforesaid tubular curtain S preferably in spaced relation with respect thereto, these vapors passing through, the housing I concurrently as regards the contact material C and are converted in the presence thereof. When hydrocarbon material is subjected to a catalytic cracking operation; the temperature of these vapors is usually substantially higher than the hereinafter specifled temperature of the liquid hydrocarbon material admitted to the atomizer A in order that the heat content of said vapors may assist as regards vaporization of the liquid hydrocarbon material last named and provide a desired control on the relative quantities of contact material and hydrocarbon material traversing the housing I. For the purpose stated immediately above, a casing It may be suitably secured to the lower end portion of the above described pipe 4, the arrangement being such that there is formed a chamber lta'which may be concentrically related with respect to the exterior surface of said pipe 4. The lower wall of the casing it, which preferably is disposed in alinement with or closely adjacent the plane of the annular passage 6, may comprise a circumferentially com.-

plete inclined portion having formed therein a plurality of ports or passages ltb which, preferably, are spaced equidistantly with respect to each other or substantially so. In lieu of the ports lab, it will be understood that a continuous slot or port may be utilized for the purpose ame Itctheinterior casing II. In accordance with a preferred hydrocarbon vapors under pressure sufficient to cause said vapors to enter the chamber I8 .a'nd then pass therefrom by way of the respective ports Ilb, initially, as individual vapor streams havingvelocity suflicient for the purpose hereiiinitei described.

' activated clay pellets, or synthetic silica-alumina pellets or beads, etc. having suitable major dimensicns such as between and of an inch. Other suitable catalyst for cracking include synthetic plural oxide composites, silicious or nonsilicious in character, and containing, for example, zirconia, alumina or beryllia. In lieu of a cracking operation, other types of conversion operations such, for example, as one wherein hydrocarbon material of the character referred to below is desulphurized under known conditions with catalytic contact material of the general character referred to above, or equivalent.- Or, reforming or dehydrogenation of naphthas or other normally liquid hydrocarbons may be effected in the presence of the above or other desired types of catalyst, certain of which are well known in the art.

During operation with suitable cracking contact material, liquid hydrocarbon material such, for example, as a suitable residual stock, topped or reduced crude having temperature elevated into a suitable range as, for example, from 400 1''. to 800 F. is charged continuously through the pipe I under superatmospheric pressure ranging,

' for example, from 10 lbs. to 200 lbs. per square is, 'formed in the pipe I and preceding equipment.

The liquid hydrocarbon material traversing the pipe I passes through the atomizer casing I5 and then through the sets of alined ports I50. As regards each set of alined ports I50, streams of hydrocarbon material pass, respectively, in opposite directions along substantially a straightline path which is suitably related to a horizontal thereof is a pine II which, tea with the aforesaid chamber Ila of the invention, the pipe II is traversed sultant partial or complete plugging of the outplane. These streams engage each other in headon relation between the two alined ports and,

' due to such engagement and also due to the presa common center which coincides with the longitudinal axis of the atomizer A. These of atomized liquid material merge with each other. soon after leaving the atomizer A and, in merged, condition, eng e and penetrate said curtain. SI of contact material while moving downwardly;

in inclined directions as indicated in Fig. 1.

As hereinbefore stated, the annular passage 8 restricts the downward flow of contact material through the pipe 4 and causes said contact material to form the tubular curtain S. As de scribed in my aforesaid pending application. Serial No. 766,714, the density and thickness-- characteristics of this tubular curtain maybe such that the atomized liquid material ejected: from the atomizer A is at least substantially Dre vented from passing therethrough while obtaining desired or satisfactory penetration thereof;

Should the conditions of operation be such that some of the atomized liquid material does pass through the tubular curtain S, there is a definite tendency for at least some of the atomized liquid material last named to migrate, not into engagement with the top surface of the bed B, but into.

engagement with the interior surface of the housing I and the exterior surfacesof were: spective pipes 9, when utilized. Should this hap pen during continuance of the conversion opera--, tion, there is resultant production or deposition on these surfaces, of carbonaceous material' which, in the course of time, breaks off into.

chunks of such material that move. into and through the bed B of contact material with re lets interiorly of the housing I at the bottom thereof. Should this happen to any substantial extent, it is necessary for operation of the systen; tobe discontinued for cleaning purposes. The foregoing, of course, is undesired and is at least substantially prevented as hereinafter described.

As the foregoing operation proceeds, and, in

accordance with the invention, hydrocarbon vapors such, for example, as vaporized gas oil,

but they soon merge to form a single, circumferentially complete vapor stream having gem,

erally conical exterior configuration which, while 1 forming a vapor envelope around the tubular,

curtain S of contact material, moves downwardly toward and into engagement with an outer gen-v erally annular upper surface of the bed B.

In accordance with the invention, the quantity of vapors admitted to the casing chamber Ida is suilicient and the pressure interiorly thereof is. maintained at proper magnitude to cause the I vapors, upon ejection thereof from the casing ports Itb, to have velocity sufficient, first, to reach the upper surface of the bed B as stated above and, second, to deflect any migrating atomized liquid material which traverses the tubular cur-.. tain S and effectively sweep the same into en-. gagement with the contact material forming the the interior surface of the housing I, this being desirable for the reasons hereinbefore stated.

7. Intheeventthatasmallportionofthemigrating atombed liquid materialdoespass through the aforesaid conical vapor stream, the

.latterdecreaaesthepartialpressureofsaidlast atomized liquid material which. accordinsly. b more readily vaporized by the ambient heat conversion system than would be the in view of the foregoing, it will be understood that hydrocarbon material admitted to the housing i by way of the pipes I and II is converted in the presence of the contact 'offlue gases, is admitted tothe top of the housing ibywayofapipe lo,l"lg. 1, atsucharateas to produce i pressure above the contact material in the receptacle 8 which is slightly greater than that existing in the chamber D, this being done in order to prevent passage of hydrocarbon vapors upwardly through the pipe-2. Due to this pressure relation which exists in the chamber D, hydrocarbonmaterial admitted to said chamber by way of the pipes I and II, as described above, is caused to pass downwardly concurrently as regards the gravitating contact material, this hydrocarbon material being cracked in the presence of said contact material and the resulting cracked vapors being suitably disengaged therefrom whereupon they are passed to any suitable destination by way of the hereinbefore described outlet pipe it. In known manner and by suitable means, not shown, a suitable gaseous medium such as steam is admitted to the lower portion of the housing i, below the pipe I! and under pressure above that existing at the level thereof, to prevent passage of the hydrocarbon vapors through the pipe ll.

For purposes of explanation, the invention has been described in connection with a conversion system wherein the contact material gravitates through a housing in a particular manner. Obviously, however, the invention is not to be thus limited since it is applicable to conversion systems wherein the contact material to which the atomized liquid material is applied is controlled for movement, gravitating or otherwise, in any desired manner whether freely falling or not. If freely failing, the present invention is not to be restricted to a curtain having the density and thickness characteristics of the character disclosed in my aforesaid pending application Serial No. 768,714.

As will be understood in view of the preceding description, a distinctly important feature of the invention relates to the provision of a portdenning casing utilizable for producing a stream of vapors as and for the purpose described above.

As regards the foregoing, the invention has been described in connection with a present preferred form thereof for deflecting migrating atomized liquid material to prevent or largely minimize deposition of carbonaceous material on the interior surface of a reaction or conversion housing. However, the invention is not to be thus limited since, when the stream of high velocity vapors are produced as described above, it may be desirable to prevent or minimize deposition of carbonaceous material on other surfaces interiorly of a reaction housing such, for example, as the thepartialpressm'ehadnotbeende-' 8 casingsurfaceofthe 4 thepipeleadingtheretathesurfaeeofthepipel l,etc.,anyor all of these surfacesorequivalent surfacesbeinghereinaftergenericallyrelerredto in claim language as "a surface which should be maintained free from a carbonaceous deposit.

It shall also be understood that the invention isnottobelimitedtotheutilizationofhydrocarbon vapors for the purpose described herein. Obviously, other vapors such as superheated steam may be admittedto the casing chamber its, or equivalent and utilised for deflecting pur poses in the manner described.

Theprecedingdes'crlptionrelatestocatalytlo conversion processes but the invention b not to be so limited. Thus, the contact material C may be substantially inert catalytlcaily such, for example, as fused alumina (Aluhdum). fused silica and alumina, heat-resistant quartz or quarts pebbles, fused silica, etc., this material having approximately spherical or chunk-like configuration and the major dimensions ranging between 5' and of an inch, for-example. With contact material of this character. hydrocarbon vapors.

may be admitted to the housing i by way of the pipe is under the conditions hereinbefore described and the atomizer A may be supplied with at least partially liquid phase heavy hydrocarbon material such, for example, as entire crudes. reduced or topped crudes. crude bottoms. residual or heavy bottoms, distillation residua, etc., all of which contain heavy, dinlcultly vaporizable fractions or components such as tar, asphalt or the like in various proportions. Inert contact material of the character described should gravitate through the housing while having temperature within a range between 800 I". and 1250 I". and heavy hydrocarbon material should be supplied to the atomizer A while having having temperature ranging up to 750 F. or higher. When the operation is of this character, the liquid portion of the heavy hydrocarbon material is vaporized and viscosity-broken in response to engage- 'ment thereof with the freely falling inert cona housing while having conversion temperature,

the method which comprises causing atomized liquid hydrocarbon material to pass through a part of an upper chamber of said housing for subsequent engagements with at least a substantial portion of said contact material, passing vapors along a path extending into said chamber and communicating with a port-defining zone from which a stream of said vapors is directed into the path followed by some of' the atomized liquid material migrating or tending to migrate toward a surface which should be maintained free from a carbonaceous deposit, and maintaining the velocity of the stream of vapors ejected from said zone at magnitude sufficient to deflect at least a substantial portion of the migrating liquid material from said last named path.

2. In the art of converting hydrocarbons in atomizarathemrfaceof' the presence of contact material which moves through a housing while having conversion temperature, the method which comprises causing atomized liquid hydrocarbon material to pass through a part of an upper chamber of said housing for subsequent engagement with at least a substantial portion of said contact material, passing vapors along a path extending into said chamber andcommum'cating with a port-defining zone from which a circumferentially complete stream of said vapors is directed into the path followed by some of the atomized liquid material migrating or tending to migrate toward a surface which should be maintained free from a carbonaceous deposit, and maintaining the velocity of the stream of vapors ejected from said zone at magnitude sufllcient to deflect at-least a substantial portion of the migrating liquid material from said last named path.

3. In the art of converting hydrocarbons in the presence of contact material having conversion temperature and adapted to gravitate through a part of an upper housing chamber in freely falling manner, the method which comprises causing atomized liquid hydrocarbon material to pass through a part of said chamber and to be engaged with the freely falling contact material, and passing vapors along a path extending into said chamber and communicating with a portdeflning zone from which a stream of said vapors is directed into the path followed by some of the atomized liquid material migrating or tending to migrate toward a surface which should be maintained free from a carbonaceous deposit, and maintaining the velocity of the stream of vapors ejected from said zone at magnitude suflicient to deflect at least a substantial portion of the migrating liquid material from said last named path.

4. In the art of converting hydrocarbons in the presence of contact material which moves through a housing while having conversion temperature, the method which comprises causes atomized liquid hydrocarbon material to pass from an atomizing zone disposed in an upper chamber of said housing for subsequent engagement with at least a substantial portion of said contact material, and passing vapors along a path extending into said chamber and communicating with a port-defining zone from which a circumferentially complete stream of vapors is directed downwardly around the atomizing zone and into the path followed by some of the atomized liquid materlalmigrating or tending to migrate toward the interior housing surface, and maintaining the velocity of the stream of vapors ejected from said port-defining zone at magnitude sufiicient to deflect at least a substantial portion of the migrating liquid material from said last named path.

5. In the art of converting hydrocarbons in the presence of a bed of contact material which gravitates through a housing, the method which comprises causing contact material having conversion temperature to gravitate from an upper zone to the zone defined by the upper surface of said bed while maintaining a chamber between said zones, causing atomized liquid hydrocarbon material to pass from an atomizing zone disposed in said chamber for engagement with at least a substantial portion of said contact material during movement thereof through said chamber, and passing vapors along a path extending into said chamber and communicating with a port.- deflning zone from which a circumferentially complete stream of said vapors is directed downwardly around the atomizing zone and-into the path followed by some of the atomized material migrating or tending to migrate toward the interior housing surface, and maintaining the velocity and direction of the stream of vapors ejected from said port-defining zone at magnitude such that at least a substantial portion of the migrating liquid material is deflected from said last named path and swept into engagement with the upper surface of said bed.

6. In the art of converting hydrocarbons in the presence of a bed of contact material which gravitates through a housing. the method which comprises causing contact material having conversion temperature to gravitate from an upper zone to the zone deflned by the upper surface of said bed while maintaining a chamber between said zones, causing atomized liquid hydrocarbon material to pass from an atomizing zone disposed in said chamber for engagement with at least a substantial portion of said contact material during movement thereof through said chamber, passing hydrocarbon vapors along a path extending into said chamber and communicating with a port-defining zone from which a circumferentially complete stream of said vapors is directed downwardly around the atomizing zone and into the path followed by some of the atomized material migrating or tending to migrate toward the interior housing surface, maintaining the velocity and direction of the stream of vapors ejected from said port-defining zone at magnitude such that at least a substantial portion of the migrating liquid material is deflected from last named path and swept into engagement with the upper surface of said bed. maintaining vapor pressure in said chamber sufficient to produce concurrent flow of the hydrocarbon material with respect to the contact material with resultant production of converted vapors. and disengaging said converted vapors from said contact material in a lower area of said bed.

7. In apparatus of the character described, a vertical housing, means for admitting contact material having conversion temperature to said housing for subsequent downward passage therethrough under the influence of gravity, atomizing means disposed in an upper chamber of said housing, a pipe for conducting hydrocarbon material while at least partly in the liquid phase to said atomizing means which serves to engage atomized liquid material with at least a substantial portion of said contact material, a port-defining casing disposed in said.

chamber, and means for conducting vapors into said casing from which they are ejected into the path followed by some of the atomized liquid material migrating or tending to migrate'toward a surface which should be maintained free from a carbonaceous deposit, the velocity of the vapors ejected from said casing being suflicient to deflect at least a substantial portion of the migrating liquid material from said path.

8. In apparatus of the character described, a vertical housing, means for admitting contact material having conversion temperature to said housing for subsequent downward passage therethrough under the influence of gravity, atomizing means disposed in an upper chamber of'said housing, a pipe for conducting hydrocarbon material while at least partly in the liquid phase to said atomizing means which serves to engage atomized liquid material with at least a substantial portion of said contact material. a casing disposed in said chamber above said atomising means and denning a circular row of ports, and means for conducting vapors into said casing from which they are ejected as a circumferentially complete stream into the path followed by some oi the atomized liquid material migrating or tending to migrate toward the interior suriace of said housing. the velocity oi the vapors ejected from said casing being sufllcient to defleet at least a substantial portion of the migrating liquid material from said path.

9. In apparatus oi the character described, a vertical housing. means for admitting contact material having conversion temperature to said housing ior subsequent downward passage therethrough under the influence oi gravity in freely i'alling manner and thereafter as a solid bed of contact material, atomizing means-disposed in an upper chamber of said housing, a pipe for conducting hydrocarbon material while at least .0

partlyinthsliduidphasetosaidatomizing means which serves to engage atomized liquid asoaoss 12 materialwithatleastasubstantialportionot saidcontact materiabacasingdbposadofzlld chamber above said atomiaing means and ingacircularrowoi'ports.andmeansi, ductingvaporsintosaidcasingtromwhichthey are elected as a circumierentiaily complete stream into the path 1 atomized liquid material migrating or tending to migrate toward the interior surface housing, the velocity and direction oi ejected from said casing being such that at a substantial portion of the migrating terlal is deflected from said path and engagement with the upper surface The following references are oi record in tile 0! this patent:

Commercial '1. C. C. operations on of Houdry Pioneer, vol. I, lie. 1, October, 1046. 

1. IN THE ART OF CONVERTING HYDROCARBONS IN THE PRESENCE OF CONTACT MATERIAL WHICH MOVES THROUGH A HOUSING WHILE HAVING CONVERSION TEMPERATURE, THE METHOD WHICH COMPRISES CAUSING ATOMIZED LIQUID HYDROCARBON MATERIAL TO PASS THROUGH A PART OF AN UPPER CHAMBER OF SAID HOUSING FOR SUBSEQUENT ENGAGEMENTS WITH AT LEAST A SUBSTANTIAL PORTION OF SAID CONTACT MATERIAL, PASSING VAPORS ALONG A PATH EXTENDING INTO SAID CHAMBER AND COMMUNICATING WITH A PORT-DEFINING ZONE FROM WHICH A STREAM OF SAID VAPORS IS DIRECTED INTO THE PATH FOLLOWED BY SOME OF THE ATOMIZED LIQUID MATERIAL MIGRATING OR TENDING TO MIGRATE TOWARD A SURFACE WHICH SHOULD BE MAINTAINED FREE FROM A CARBONACEOUS DEPOSIT, AND MAINTAINING THE VELOCITY OF THE STREAM OF VAPORS EJECTED FROM SAID ZONE AT MAGNITUDE SUFFICIENT TO DEFLECT AT LEAST A SUBSTANTIAL PORTION OF THE MIGRATING LIQUID MATERIAL FROM SAID LAST NAMED PATH. 